A homemade D&D module from 1981 called G2 Squared: Habitition of the Stone Giant Lord is available for free download at PlaGMaDA. It's typewritten, illustrated, has hand-drawn maps on graph paper, and full of typos (like the one in the module title). It's also full of gonzo fun stuff like a kitchen full of female giants who defend themselves by throwing (giant) kitchen utensils and an introduction that includes this line: "If the adventurers return without sufficient evidence of kills they may be hanged or otherwise executed..." There's also the advice to "Trust no one!" (Years before the publication of Paranoia, but keeping your laser handy would be helpful too -- if you only had one). BTW, the designer was 14 at the time.

Go download this amateur gem now either by viewing the scanned pages at PlaGMaDA or by downloading a PDF version here.

Edit: As noted in a comment below, this PDF was created by mwschmeer at his Rended Press blog. A CBZ version is also available there.